A step down transformer reduces $ 220 \mathrm{~V} $ to $ 110 \mathrm{~V} $. The primary draws $ 5 \mathrm{~A} $ of current and secondary supplies $ 9 $ A. The efficiency of the transformer is

Question

A step down transformer reduces $ 220 \mathrm{~V} $ to $ 110 \mathrm{~V} $. The primary draws $ 5 \mathrm{~A} $ of current and secondary supplies $ 9 $ A. The efficiency of the transformer is, $ 20 \% $, $ 44 \% $, $ 90 \% $, $ 100 \% $

MARKS App · Accepted Answer

For a transformer, we all know that: η = P o P i × 100 = E s i s E p i p × 100 . This gives us: % e f f i c i e n c y = P o u t P i n × 100 = 110 × 9 220 × 5 × 100 = 90 %

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